Increased thioredoxin levels are related to insulin resistance in familial combined hyperlipidaemia.

BACKGROUND: Thioredoxins (TRX) are major cellular protein disulphide reductases that are critical for redox regulation. Oxidative stress and inflammation play promoting roles in the genesis and progression of atherosclerosis, but until now scarce data are available considering the influence of TRX activity in familial combined hyperlipidaemia (FCH). Since FCH is associated with high risk of cardiovascular disease, the objective of the present study was to assess oxidative stress status in FCH patients, and evaluate the influence of insulin resistance (IR). MATERIALS AND METHODS: A cohort of 35 control subjects and 35 non-related FCH patients were included, all of them nondiabetic, normotensive and nonsmokers. We measured lipid profile, glucose and insulin levels in plasma, and markers of oxidative stress and inflammation such as oxidized glutathione (GSSG), reduced glutathione (GSH) and TRX. RESULTS: Familial combined hyperlipidaemia subjects showed significantly higher levels of GSSG, GSSG/GSH ratio and TRX than controls. In addition, FCH individuals with IR showed the worst profile of oxidative stress status compared to controls and FCH patients without IR (P < 0·01). TRX levels correlated with higher insulin resistance. CONCLUSION: Familial combined hyperlipidaemia patients showed increased TRX levels. TRX was positively correlated with IR. These data could partially explain the increased risk of cardiovascular events in primary dyslipidemic patients.

Xanthine oxidoreductase polymorphisms: influence in blood pressure and oxidative stress levels.

OBJECTIVES: Oxidative stress can modulate blood pressure levels in different models. Xanthine oxidoreductase is one of the enzymes producing free radicals in the cardiovascular system, and it can contribute to the increment of the oxidative stress and, consequently, blood pressure. We analyzed the association between the -337GA and 565+64CT polymorphisms of the xanthine oxidoreductase gene with blood pressure and oxidative stress levels. METHODS: These polymorphisms were studied in a case-control study (185 patients with hypertension and 385 normotensive controls), we found that these polymorphisms were related to blood pressure levels. This association was high in patients with hypertension and showed an additive effect but did not increase the risk of developing hypertension. We studied an additional and independent sample of patients with hypertension (n=100) to know the association of these polymorphisms with oxidative stress levels. RESULTS: We found that these polymorphisms were related to blood pressure levels. This association was high in hypertensive patients and showed an additive effect, but does not increase the risk of developing hypertension. We have found that the same alleles related with higher blood pressure-337A and 565+64C were related with increased oxidative stress in patients with hypertension. CONCLUSIONS: Our results suggest that polymorphisms -337GA and 565+64CT of xanthine oxidoreductase gene are related with blood pressure and oxidative stress in hypertension, adding evidence to the role of xanthine oxidoreductase and oxidative stress in blood pressure.